Noninvasive detection of corrosion, MIC, and foreign objects in fluid-filled pipes using leaky guided ultrasonic waves

ABSTRACT

Ultrasonic energy in the form of guided waves is launched into the wall of a fluid-filled container. The guided wave propagates around the circumference of the container from a transmitting transducer to a receiving transducer. Part of the guide wave energy leaks into the fluid in the form of bulk waves, reflects off the inner wall on the other side and enters back to the receiving transducer trailing the direct wave. Analysis of the received waves determines the presence of corrosion pitting and MIC nodules on the container inner wall, and fluid level. In addition, it determines whether foreign objects are inside the container. The guided waves are created with wideband transducers excited at certain frequencies that depend on the material and geometry of the part being measured. The leakage energy is maximized with a shaped tone burst pulse at the specified frequency. The energy and energy ratio of both the direct and leakage fields are measured and related to the container inner wall condition and the presence of any foreign objects in the fluid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation part of and claims the benefit ofU.S. application Ser. No. 09/613,704 Filed Jul. 11, 2000 now U.S Pat.No. 6,367,328 and a continuation of application Ser. No. 09/613,705,filed Jul. 11, 2000 now U.S. Pat No. 6,363,788, the disclosure of whichis incorporated by reference for all purposes.

This application is related to “NONINVASIVE DETECTION OF CORROSION, MIC,AND FOREIGN OBJECTS IN FLUID-FILLED PIPES USING LEAKY GUIDED ULTRASONICWAVES” by Gorman et al., U.S. Ser. No. 60/143,366, filed Pursuant to 37C.F.R. 1.71 (e), Applicants note that a portion of this Jul. 12, 1999and to “NONINVASIVE DETECTION OF CORROSION, MIC, AND FOREIGN OBJECTS INFLUID-FILLED PIPES USING LEAKY GUIDED ULTRASONIC WAVES” by Gorman etal., U.S. Ser. No. 60/203,661, filed May 12, 2000. This application isalso related to “NONINVASVE DETECTION OF CORROSION, MIC, AND FOREIGNOBJECTS IN PIPES USING GUIDED ULTRASONIC WAVES” by Gorman and Ziola,U.S. Ser. No. 60/209,796, filed Jun. 5, 2000 and to “NONINVASIVEDETECTION OF CORROSION, MIC, AND FOREIGN OBJECTS IN PIPES USING GUIDEDULTRASONIC WAVES” by Gorman and Ziola, Ser. No. 09/613,705 filed Jul.11, 2000. This application claims priority to each of these priorapplications, pursuant to 35 U.S.C. §119(e), as well as any otherapplicable rule or statute.

FIELD OF THE INVENTION

This invention relates to noninvasive testing of the internal conditionsof fluid-filled containers such as pipes, cylinders, etc., and to novelultrasound methods for testing these internal conditions.

COPYRIGHT NOTICE

Pursuant to 37 C.F.R. 1.71 (e), Applicants note that a portion of thisdisclosure contains material which is subject to copyright protection.The copyright owner has no objection to the facsimile reproduction byanyone of the patent document or patent disclosure, as it appears in thePatent and Trademark Office patent file or records, but otherwisereserves all copyright rights whatsoever.

BACKGROUND OF THE INVENTION

Detecting inner wall corrosion in containers such as pipes, conduits,cylinders, tanks, pressure vessels, etc. has been a longstanding concernin many industries. For example, MIC (microbiologically influencedcorrosion) in water systems is of particular concern. Microbes live inwater everywhere and are difficult to kill. Corrosion pitting, slimyfluid and rusty nodules are often the products of MIC. Such corrosionand foreign objects cause wall thinning and reduction of flow area thatare detrimental to the structural performance of pipes or othercontainers, and can sometimes lead to disastrous consequences. Chemical,petroleum, water utility, fire and power industries have been battlingMIC and other forms of internal container (e.g., pipe) corrosion (e.g.,in water and other fluid storage and/or conducting systems) for manyyears.

Many nondestructive or noninvasive methods have been applied, withvarying degrees of success, to locating MIC and assessing its effects.X-ray and gamma ray radiographs provide images that can be used to gaugethe presence of MIC, the amount of occlusion and wall thinning. However,drawbacks of these methods include slow inspection speed, high cost andsafety/health concern issues.

Ultrasonic thickness gauging is used routinely to measure wall thicknessin refinery piping and tanks. Compared to radiography, ultrasound ischeaper and doesn't emit harmful radiation. A single thickness gaugemeasurement is much faster than radiography, but it only covers alocalized area the size of the transducer used in the measurement. Thus,to obtain the thickness information over a large area, the ultrasonicthickness gauge method may not be as fast as radiographic methods. Moreimportantly, a wall thickness reading at a given point depends on goodthrough-thickness echoes so that an accurate time can be measured. Roughcorroded internal wall surface and porous MIC nodules make it difficultto get a valid reading. Often the wall thickness reading is greater thannominal. In some cases, no echoes are available because the ultrasonicenergy is simply absorbed or scattered. The ultrasonic thickness gaugeis not used to detect the existence of, e.g., slimy fluid either.

The present invention overcomes these and other limitations of the priorart by providing new methods, apparatus and integrated systems formeasuring features of fluid filled containers (e.g., pipes, tanks,barrels, drums, cylinders, plates and other structures) and a variety ofother features that will become apparent upon complete review of thefollowing.

SUMMARY OF THE INVENTION

A “leaky guided wave ultrasound” (LGWU) method is provided for fast andreliable detection of features on the internal walls of containers(e.g., pipes, conduits, tanks, barrels, drums, cylinders, plates andother appropriate structures that will be apparent upon further reviewof the following), such as container wall irregularities, loss of wallmaterial, pitting, corrosion, MIC, or the like, as well as for thedetection of foreign objects, e.g., in fluid-filled containers. Materialin the pipes, whether deliberate (e.g., container structural features)or unintended (e.g., ice or foreign objects) can also be detected.

The methods, devices and systems herein are generally applicable tostructures and systems that can be configured to comprise one or moregas, solid or fluid. The methods, systems and devices herein areparticularly well-suited to structures and systems comprising fluidfilled containers.

In the methods of the invention, a transmitting transducer (e.g., placedcircumferentially on the outside of the container) excites a guidedwave, and part of its energy leaks into a material such as a fluid in acontainer. The leaking wave travels through the fluid or other material,reflects off the container inner wall and enters the receivingtransducer.

The LGWU method measures both the direct field, and the leakage fieldinside the fluid generated by the guided ultrasonic waves. Since theleakage field interacts directly and, typically, only, with the fluidand inner container wall, the LGWU method is able to reliably detectcorrosion, MIC and other features on container inner walls (e.g., theinsides of pipes), as well as fluid level and composition, includingforeign objects inside the fluid.

By calibrating against the measured direct field, the LGWU method is notsensitive to the container outside wall surface condition, such as theexistence of paint, rust or dust. In addition, a single LGWU measurementcovers a significant portion of the circumference of the container.Therefore, as few as two or three LGWU measurement locations can provideapproximately 100% inspection coverage of an entire containercircumference. Thus, the inspection speed is faster than any priormethods. The LGWU method can also be used to accurately detect fluidlevel (e.g., whether water, hydrocarbon or other fluid type) in thecontainer, or the existence of ice in the container, e.g., due to frozencondensation water.

The present invention also provides devices, apparatus, integratedsystems and kits for practicing the methods of the invention. Forexample, the invention provides an integrated system and/or device fordetecting corrosion and MIC on the inner wall of fluid-filled containerssuch as pipes, foreign objects in the fluid, and/or fluid level usingleaky guided wave ultrasound (LGWU).

The system/device includes components for performing the method above,such as a transmitting transducer and a receiving transducer or a singlepulse-echo transducer configured for placement at circumferential orlongitudinal positions of a fluid-filled container, a wave generator orpulser which produces a shaped tone burst pulse at a specified frequencyor uses a resonant transducer excited by a spike or rectangular pulse tocreate the specified frequency and detection modules consisting of areceiving transducer or transducers connected to both digital and analogamplifiers and filters, analog to digital converters controlled bysoftware or firmware and digital electronic storage media for thepurpose of measuring both a direct field and a leakage field, softwareand/or firmware for analyzing the direct and leakage field signals,thereby providing an indication of existence of corrosion and MIC on thecontainer inner wall, foreign objects inside the fluid and fluid level.

The guided wave can be excited at a selected frequency and angle tomaximize the leakage field for selected container ODs and materials.Other suitable wave characteristics can also be selected or modulated inthe methods and systems herein; e.g., the amplitude of a given phasepoint on the tone bursts can be modulated or selected.

The device, apparatus, kit or system can include a computer or computerreadable medium having an instruction set for controlling the systeme.g., for controlling the transmitting transducer the guided wavegenerator, or the like. The computer or computer readable medium (ormultiple associated computers or computer media) can include otherrelevant instruction sets, e.g., for measuring the direct field and theleakage field, reporting the results of the measurement to a user,running a graphical display of the relevant results, or the like. Kitscan include any of the apparatus or integrated systems elements pluscontainers for storing the apparatus or system elements, instructions inusing the apparatus or integrated systems elements, e.g., to practicethe methods herein, packaging, etc.

A presently preferred method/system is to use an arbitrary functiongenerator (which, e.g., generates a pulse at a user-defined frequency)in combination with a wideband transducer, so that a range offrequencies can be excited and received. This approach typically usescomputer software to control and shape the pulse and frequency alongwith wideband amplifiers and filters. The system device includes thegeometrical configurations and various media that can be used to couplethe transducers to the container, tank or structure.

Further objects and advantages of the invention will become apparentfrom a consideration of the drawings and description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic of the LGWU measurement system.

FIG. 2 panels A-C is a schematic of three different ways of implementingthe LGWU transducer coupling system 3 and 4 in FIG. 1.

DETAILED DISCUSSION OF THE INVENTION List of Reference Numerals

The reference numerals below correspond to elements of the figures.

1—fluid filled pipe or other container

3—transmitting transducer coupling system

4—receiving transducer coupling system

5—arbitrary function generator

6—RF amplifier

7—RF receiver—gain circuitry

8—RF receiver—filter circuitry

9—2-channel A/D converter

10—computer

11—energy field detection/display module comprising LGWU elements

12—wedge shoe

13—water pump

14—vacuum pump

15—contact transducer

16—water bucket

17—rubber wheel

18—immersion transducer

19—Air-coupled transducer

INTRODUCTION: GUIDED WAVE ULTRASONIC TESTING

Guided ultrasonic waves can be used to overcome the speed limitation ofa standard ultrasonic thickness gauge. The standard thickness gaugeinvolves a standard “flashlight” beam pulse-echo ultrasonic testing (UT)at a point, with only one transducer being used as both the transmitterand receiver.

In contrast, a guided wave ultrasound (GWU) travels in the arealdirection along the axis or circumference of the pipe or other containerwall, rather than in the thickness direction. Typically, two transducersplaced on the wall surface, several inches apart are used in GWU; oneacts as the transmitter and the other as the receiver.

The physics of these different approaches is quite different, as mightbe expected. Standard UT involves bulk or free waves at wavelengths muchsmaller than the wall thickness, and the waves can be treated as smalltight packets travelling inside the wall in the thickness direction. GWUwavelengths are on the order of the wall thickness or greater, and thewave packets occupy the whole wall thickness and travel in the arealdirection along the wall. Thus, the GWU can propagate great distancesalong the wall area only slightly diminished, like light in opticalfibers. Bulk waves propagate without dispersion, while GWU waves aredispersive. In GWU, different frequencies in the wave packet propagateat different velocities and pulses will change shape as they travelalong. Finally, instead of the two wave modes as in standard UT, thereare many modes in GWU.

The physics of guided waves was described by Lamb in 1917, and Mindlinin the 1950s & 1960s, but little technology in industrial containertesting resulted until the early 1990s. As advanced microprocessors madethe difficult GWU computations possible, there was an increased interestin the industrial application of GWU.

Currently, there are at least two GWU applications in container testing.The first is the container thickness measurement where the receivedpulse travels directly from the transmitter to the receiver along thecontainer wall a known distance at a known velocity. Since the spacingbetween the transmitter and receiver is much greater than the transducersize, the GWU thickness measurement is much faster than the ultrasonicthickness gauge measurement. Note that the GWU wall thickness is anintegrated wall thickness over the line between the transmitter andreceiver. The other GWU application is for crack detection, e.g., wherea single transducer is used as both the transmitter and receiver tolisten to the GWU echoes from cracks in the wall. In both cases, the GWUmeasurements rely on the GWU waves whose energy is distributed throughthe whole wall thickness.

Since the GWU wave energy is distributed through the entire wallthickness, the GWU method is sensitive to both the container inner andouter wall surface conditions. The sensitivity of the GWU measurement tothe outer wall surface can be adjusted by varying the wave mode andfrequency selected. Paint and dust have little effect on the measurementdue to the large impedance and stiffness mismatch to the containermaterial.

However, the sensitivity of conventional UT and GWU is limited. MICnodules, slimy fluid and foreign objects in the container can goundetected since they may not affect the waves.

In the present invention, a “leaky guided wave ultrasound” (LGWU) systemis utilized. In the system, a transmitting transducer excites a guidedwave, and part of its energy leaks into fluid in a pipe or othercontainer. The leaking wave travels through the fluid, reflects off thecontainer inner wall and enters the receiving transducer. The LGWUmethod measures both the direct field, and the leakage field inside thefluid generated by the guided ultrasonic waves. Since the leakage fieldinteracts directly with the fluid and inner container wall, the LGWUmethod is able to reliably detect corrosion, MIC and other features onthe container inner wall, as well as fluid composition, includingforeign objects inside the fluid.

DESCRIPTION OF PREFERRED EMBODIMENTS

It will be understood that the methods and apparatus herein are used forexamining, e.g., the inner walls and contents of any type of container(e.g., any fluid filled container). As used herein, the term “container”is intended broadly to apply to any structure that can be said toencompass a given volume, or even to define a portion of a given volume.Such structures include, without limitation, pipes and other conduits,whether partly or fully open or partly or fully closed, tanks,cylinders, plates, pressure vessels, etc. In general, when specificallyreferring to any of these (e.g., pipes) herein, it will be appreciatedthat similar methods, apparatus, devices systems, etc., can be appliedto any similar structural form.

FIG. 1 shows a basic schematic of a leaky guided wave ultrasound (LGWU)system of the invention. One of skill will recognize a variety offeatures that may be substituted to achieve essentially similar results;however, for clarity, the following discussion focuses on this basicsystem.

The system, which interfaces, e.g., with fluid filled pipe or othercontainer 1, comprises transmitting transducer coupling system 3,receiving transducer coupling system 4, RF amplifier 6, RF receiver gain7 and filter 8 circuitry, computer 10 with plug-in arbitrary functiongenerator 5, 2-channel A/D converter 9, and an energy fielddetection/display module 11. The output of arbitrary function generator5 is connected to the input of RF amplifier 6. This output is optionallyinput into channel 1 of A/D) converter 9 to provide a reference signal.The RF amplifier 6 output is connected to transmitting transducer 3. Thereceiving transducer is connected to the input of the RF receiver gain 7and filter 8 circuitry. The output of the RF receiver is connected tothe channel 2 input of A/ID converter 9. Energy field detection/displaymodule 11 controls the signal generation, acquisition and displayfunctions. The energy field detection module optionally comprises ananalog to digital converter, which converter converts direct or leakagefield energy into digital format data. Arbitrary function generator 5can, e.g., generate a pulse at a user defined frequency. Energy fielddetection/display module 11 can be e.g., a software module in computer10, or module 11 can be a separate device with software elements.

Software and/or hardware present in energy field detection/displaymodule 11 (this module can include software, firmware, hardware, or acombination thereof, for data analysis and/or display, including analogand/or digital display formats) controls function generator 5 togenerate a tone burst pulse with selectable frequency, amplitude, shape,cycles in the pulse and pulsing rate. As noted, the module can includestand alone software or hardware (e.g., dedicated microprocessorhardware), or, commonly, can simply include software present in computer10. The shaped tone burst pulse out of function generator 5 is sent tothe channel 1 input of A/D converter 9 and displayed on the computerscreen (depicted as the upper trace). The same pulse is also sent e.g.,simultaneously, to the input of RF amplifier 6. After amplification, thepulse is then sent to wideband transmitting transducer 3 to excite theguided wave in the container wall. Part of the excited guided wave leaksinto the fluid in the form of a bulk wave (leakage field), while theother part continues its propagation along the circumference in themetal wall (direct field). The leakage wave travels inside the fluid,reflects off the inner wall and enters back to the wideband receivingtransducer 4 trailing the direct wave. The received signal is thenamplified and filtered by gain 7 and filter 8 circuitry of the RFreceiver.

The conditioned signal is then sent to channel 2 input of A/D converter9, and displayed on the computer screen (depicted as the lower trace).Note that display/software for energy field detection/display module 11can also define data acquisition parameters such as the A/D rate, totaldigitized time window, etc. Alternately, these parameters can becontrolled separately, e.g., using a different module in computer 10, ora second computer.

A user can create a calibration wave, using the software, for eachcontainer wall thickness, diameter, and material. This wave can bedisplayed, allowing the user to visually compare the calibration wavewith the wave from the container being inspected. This is a helpfulcomponent of the system, providing accuracy and reliability when in useby trained personnel. It should be noted that this form of display isnovel to the present system.

For pipes or other containers of different OD and wall thicknesses, aspecific group of frequencies and transducer coupling systems isselected to maximize the excitation of the leakage field from thewell-known leakage theory of guided waves. The frequency range for LGWUwave generation is between about 100 kHz to about 1.5 MHz, with sensorangles between about 45° and about 70° from the normal to the containersurface. The amount of the leakage energy is determined, e.g., by thefrequency of the ultrasound, properties of the coupling medium and thewall material and thickness. If corrosion exists on the wall innersurface, both the direct and leakage fields are reduced. If there is anobstruction in the container, the leakage energy is reduced due toblockage and scattering. This phenomenon can be used to detect innerwall container features such as corrosion and MIC nodules on the innerwall, or ice due to frozen condensation water (ice which is free insolution can be detected as well, as a foreign object in the fluid), aswell as the presence of denser fluids such as slimy fluid (or less densefluids, such as hydrocarbon-based fluids), the existence of foreignobjects in the fluid (ice, dirt, debris, organic matter, rodents, etc.),as well as fluid level in the container. Data analysis/display softwarefor energy field detection/display module 11 analyzes the direct fieldenergy, the leakage field energy and the ratio of leakage/direct fieldenergy, and then classifies the condition of the container (of course,separate software modules can be substituted in place of a singlesoftware module).

Generally, the software controls the transmission and reception of theultrasonic pulse, performs specific analyses to evaluate and categorizethe container condition, and displays both raw signals and analysisresults in a user friendly format. To measure properly, the type ofcontainer is input into a database which can be added to as necessary ordesired. This database includes, e.g., the material, schedule anddiameter of the container, etc.

A feature of the software optionally provides calibration. For example,by selecting a “CAL” button on the screen, a standard waveform for a newcontainer of that material, schedule and diameter is displayed justabove that of the container being tested. This provides the operatorwith a useful visual comparison to supplement the analysis algorithms.This becomes particularly helpful when the container schedule changesunexpectedly, as it often does, e.g., in older systems that haveundergone repairs.

The following provides a basic flowchart/outline of the operationsperformed by an exemplar software module:

1. Select pipe or other container parameters (schedule and diameter).

2. Select measurement, e.g., thickness or obstruction.

3. Select calibration waveform (this is optional)

4. Acquire data: pulse shape and frequency are downloaded from aninternal database; the pulse is sent out of the pulser board in thecomputer. The pulse is amplified and excites the transmittingtransducer. The pulse is detected by the receiving transducer, fed toreceiver electronics, and then fed into an analog to digital converterand stored in digital electronic format in the computer.

5. Analyze data: received waveform(s) is/are compared with calibrationsignal(s) and direct waves are compared to energies of multiple leakywaves as well as the direct wave.

6. Raw data is displayed as received signal(s) and analysis result(s).

7. Stored calibration pulse waveform for good container(s) aredisplayed.

In general, the LGWU method can be used on pipes or other containerswithout much surface preparation. For each measurement, the direct andleakage fields cover a significant portion of the containercircumference. Therefore, only two or three measurements in thecircumferential direction are needed to completely inspect the containerinner wall and the fluid inside. Thus, the method can be used todetermine the amount of any flow restriction as well as the existence ofany occlusion in the container.

To detect fluid level, one moves the transducers axially above or belowthe fluid level. If the transducers are below the fluid level, thesystem records the existence of the leakage field. If above the fluidlevel, the leakage field is absent. For each axial position, a singlemeasurement is sufficient to detect the existence of fluid inside thecontainer (although, of course, multiple measurements can also be made,if desired).

Water-coupled wideband transducers, dry-coupled wideband transducers,and an air-coupled wideband transducer are all examples of appropriatetransducers for the present invention. FIG. 2 shows three different waysof implementing LGWU transducer coupling system 3 and 4 in FIG. 1, andmany others will be apparent to one of skill, in light of completereview of this disclosure. For the water-coupled system shown in FIG. 2,panel A, contact transducer 15 is mounted on wedge shoe 12 withultrasonic gel in between. A bottom surface of shoe 12 is machined tomatch the contour of the container outer surface. In addition, waterholes are drilled into the bottom surface. Water tubes are used toconnect the water holes to water pump 13 in water bucket/container 16,and to vacuum pump 14 attached to the side of water bucket/container 16above water line. Water pump 13 pumps water to the shoe bottom toprovide coupling between the wedge shoe and container outer surface.Excess water is sucked up by vacuum pump 14 and flows back into waterbucket 16. For the dry-coupled system shown in FIG. 2, panel B,immersion transducer 18 is placed inside a fluid-filled rubber wheel 17(it will be appreciated that materials such as polymers, plastics or thelike can be substituted for the rubber on the rubber wheel). The wheelrotates while the transducer sits at a fixed angle towards thecontainer. The fluid couples the ultrasound from the sensor to therubber wheel. The rubber on the outside surface of the wheel deforms tothe outside diameter of the container, and is coupled to the containerusing a small amount of ultrasonic couplant.

An air-coupled system like that in FIG. 2, panel C can also be used.Air-coupled transducer 19, such as an electromagnetic transducer (EMAT),is placed at an appropriate distance above (or otherwise proximal to)the container.

The coupling system couples ultrasound out of the transmitting sensorand into the container to become guided waves propagating away from thesystem along the container wall. At the same time, it also couples theultrasound traveling towards the receiving coupling system into thereceiving transducer.

Accordingly, the leaky guided wave ultrasound (LGWU) system provides afast and reliable device to detect inner wall container features such ascorrosion, ice and MIC on the container inner wall, fluidic featuressuch as fluid density and composition, ice, dirt and other foreignobjects inside the fluid, and fluid level. These detection abilities areextremely useful in many industrial, commercial and even residentialsettings, i.e., essentially anywhere fluid filled containers are found.For example, without limitation, fire suppression systems, gascylinders, water supply and removal (sewage) systems, refineries, watertreatment facilities, petroleum supply stations and many othersextensively utilize fluid filled containers.

As noted, while the above description contains many specific examples,these should not be construed as limitations on the scope of theinvention, but rather as an exemplification of embodiments thereof. Manyother variations are possible and will be apparent to one of skill uponreview of this disclosure. For example, one can perform the fluid leveldetection using a more efficient configuration by placing thetransducers axially rather than circumferentially. If the transducersare below the fluid level, the direct wave energy is the smallest due tomaximum leakage. On the other hand, if the transducers are above thefluid level, the direct wave energy is the strongest due to the absenceof leakage. Another example is to apply the same LGWU system to inspectfluid containers of non-circular shapes, such as cubes and cones (i.e.,conic and cubic shapes, or any other regular or irregular shapes).

Other uses of the LGWU method include detection of objects or materialsinside or behind other structures near or attached to a wall. Forexample, the trays inside a distillation column, vanes and partitionsinside a tank, hat stiffeners in an aircraft wing filled with fuel,reinforcements and other attachments for walls of a fluid container,etc. The advantage of using the LGWU method in those applications isthat one can determine whether something is attached to the wallanywhere on the circumference, without having to inspect the entirecircumference point by point. This approach is much faster, morereliable and more versatile than standard UT point-by-point methods.

Variations of transducer coupling systems 3 and 4, other than thosespecifically described above, can also be used. These include, but arenot limited to, dry couplant, laser, electrostatic transducers, airscanners, rollers, touch and release fixtures, back reflected energywith a single transducer etc. Similarly, plug-in function generator 5can comprise or be replaced by a stand-alone analog function generator,and computer 10 with plug-in A/D converter 9 can also be substituted,e.g., by a digital or analog oscilloscope. The system optionallyincludes an analog energy detector and analog or digital display.

The foregoing description of embodiments of the invention has beenpresented for purposes of illustration and description. The descriptionis not intended to be exhaustive or to limit the invention to theprecise form disclosed, and many modifications and variations arepossible in light of the above teaching. Such modifications andvariations which may be apparent to a person skilled in the art arewithin the scope of this invention. All patent documents andpublications cited above are incorporated by reference in their entiretyfor all purposes to the same extent as if each item were so individuallydenoted.

What is claimed is:
 1. A method, comprising: generating a guided wave ina fluid filled container; measuring both a direct field and a leakagefield produced by the guided wave; and, correlating the measured directand leakage fields to the existence of at least one feature, fluid ormaterial inside of the fluid filled container.
 2. The method of claim 1,wherein the container comprises a pipe, a conduit, a tank, a barrel, adrum, a cylinder, a plate, or a combination thereof.
 3. The method ofclaim 1, wherein the container comprises a circular region, a conicregion, a cubic region, or a combination thereof.
 4. The method of claim1, wherein the feature, fluid or material comprises: corrosion on aninner wall of the fluid-filled container, MIC on an inner wall of thefluid-filled container, ice on an inner wall of the fluid filledcontainer, ice in the fluid in the fluid filled container, a foreignmaterial in the fluid in the fluid filled container, a fluid level ofthe fluid in the fluid filled container, a fluid density of the fluid inthe fluid filled container, or any combination thereof.
 5. The method ofclaim 4, wherein said corrosion comprises pitting or loss of wallmaterial on the container inner wall.
 6. The method of claim 4, whereinsaid MIC comprises microbiology-induced corrosion.
 7. The method ofclaim 1, wherein the feature, fluid or material comprises: a floatingsolid, a slimy fluid, or a material attached to an inner wall of thecontainer.
 8. The method of claim 1, wherein the guided wave isgenerated with a transmitting transducer, wherein the transducercomprises a water-coupled wideband transducer, a dry-coupled widebandtransducer, or an air-coupled wideband transducer.
 9. The method ofclaim 1, wherein the guided waves are waves excited at a selectedfrequency and angle to maximize the leakage field for a selectedcontainer OD, material, or both OD and material.
 10. The method of claim1, wherein said measuring includes recording and analyzing the directfield energy, the leakage field energy and the energy ratio of leakagefield energy to direct field energy.
 11. The method of claim 1, whereinan amplitude of a given phase point on a tone burst that produces theguided wave is selected or modulated.
 12. The method of claim 1, whereinthe direct field is part of a received signal produced by guided wavepropagation along the container.
 13. The method of claim 1, wherein theleakage field is part of a received signal for a leaky bulk wavepropagating inside the fluid.
 14. The method of claim 1, comprisingplacing a transmitting transducer and a receiving transducer atlongitudinal or circumferential positions on the fluid filled container,wherein the transmitting transducer generates the guided wave and thereceiving transducer receives a signal corresponding to the direct andleakage fields.
 15. The method of claim 1, wherein the guided waves aregenerated with a shaped tone burst at a selected frequency.
 16. Anintegrated system, comprising: a transmitting transducer; and, an energyfield detection module configured to measure a direct and a leakagefield in a fluid filled container, which direct and leakage fields areproduced in the fluid filled container by the transmitting transducer,thereby providing an indication of a container feature, a fluidcomposition, or a presence of a material inside of the fluid filledcontainer.
 17. The integrated system of claim 16, wherein the containercomprises a pipe, a tank, a barrel, a drum, a cylinder, a plate, or acombination thereof.
 18. The integrated system of claim 16, wherein thecontainer comprises a circular region a conic region, a cubic region, ora combination thereof.
 19. The integrated system of claim 16, whereinthe container feature, the fluid composition or the presence of thematerial comprises: corrosion on an inner wall of the fluid-filledcontainer, MIC on an inner wall of the fluid-filled container, ice on aninner wall of the fluid filled container, ice in the fluid in the fluidfilled container, foreign material in the fluid in the fluid filledcontainer, a fluid level of the fluid in the fluid filled container, afluid density of the fluid in the fluid filled container, or acombination thereof.
 20. The integrated system of claim 16, comprising aguided wave generator coupled to the transmitting transducer, whichguided wave generator produces a tone burst at a selected frequency, anda computer or computer readable medium comprising an instruction setthat controls the transmitting transducer, the guided wave generator, orboth.
 21. The integrated system of claim 16, the energy field detectionmodule comprising a computer or computer readable medium comprising aninstruction set for measuring the direct field and the leakage field.22. The integrated system of claim 16, the energy field detection modulecomprising a computer or computer readable medium comprising aninstruction set for measuring the direct field and the leakage field,and an additional instruction set for reporting the results of themeasurement to a user.
 23. The integrated system of claim 22, saidinstruction set comprising instructions for recording and analyzing thedirect field energy, the leakage field energy and the energy rate ofleakage field energy to direct field energy.
 24. The integrated systemof claim 16, wherein the transmitting transducer comprises awater-coupled wideband transducer, a dry-coupled wideband transducer, oran air-coupled wideband transducer.
 25. The integrated system of claim16, wherein the energy field detection module comprises an analog todigital converter, which converter converts direct or leakage fieldenergy into digital format data.
 26. The integrated system of claim 25,the energy field detection module comprising a digital display, whichdigital display provides a user viewable display of the digital formatdata.
 27. The integrated system of claim 16, wherein the energy fielddetection module comprises an analog energy detector and an analogdisplay.
 28. The integrated system of claim 16, the energy fielddetection module comprising means for measuring the direct and leakagefield.
 29. The integrated system of claim 16, comprising the fluidfilled container and a receiving transducer, wherein the receivingtransducer and the transmitting transducer are places at longitudinal orcircumferential positions on the fluid filled container.
 30. Theintegrated system of claim 16, comprising a guided wave generator whichproduces a shaped tone burst at a specified frequency.
 31. A device,comprising: a receiving transducer operably coupled to an energy fielddetection module, which module is configured to measure a direct and aleakage field detected by the receiving transducer when in contact witha wall of a fluid filled container, thereby providing an indication ofcontainer features, fluid composition, or the presence of materialsinside of the fluid filled container.
 32. The device of claim 31,wherein the container comprises one or more pipe, tank, barrel, drum,cylinder, or plate.
 33. The device of claim 31, wherein the containercomprises one or more circular region, conic region, or cubic region.34. The device of claim 31, wherein the container features, fluids orother materials comprise one or more of: corrosion on an inner wall ofthe fluid-filled container, MIC on an inner wall of the fluid-filledcontainer, ice on an inner wall of the fluid filled container, ice inthe fluid in the fluid filled container, foreign material in the fluidin the fluid filled container, fluid level of the fluid in the fluidfilled container, or fluid density of the fluid in the fluid filledcontainer.
 35. The device of claim 31, comprising a computer or computerreadable medium comprising an instruction set for measuring the directfield and the leakage field and an additional instruction set forreporting the results of the measurement to a user.
 36. The device ofclaim 35, the instruction set comprising instructions for recording andanalyzing the direct field energy, the leakage field energy and theenergy ratio of leakage field energy to direct field energy, or a ratioof another wave characteristic of the leakage field to direct field. 37.The device of claim 36, wherein the other wave characteristic isamplitude of given phase point on the tone burst.
 38. The device ofclaim 31, wherein the transducer comprises a water coupled widebandtransducer, a dry-coupled wide band transducer, or an air-coupledwideband transducer.
 39. The device of claim 31, comprising a computerwith a plug-in arbitrary function generator and analysis/displaysoftware.
 40. The device of claim 39, comprising a 2-channel A/Dconverter.
 41. The device of claim 40, wherein the arbitrary functiongenerator generates a pulse at user-defined frequency.
 42. The device ofclaim 40, wherein the arbitrary function generator generates a pulse ata user-defined frequency and wherein an output of the arbitrary functiongenerator is connected to a first channel input of the A/D converter.43. The device of claim 31, further comprising a transmitting transducercoupling system, a receiving transducer, a receiving transducer couplingsystem, an RF amplifier, RF receiver gain and filter circuitry, acomputer with a plug-in arbitrary function generator, a 2 channel A/Dconverter, and analysis/display software.
 44. The device of claim 43,wherein the arbitrary function generator generates a pulse ofuser-defined frequency and wherein: the output of the arbitrary functiongenerator is connected to a first channel input of the A/D converter andto an input of the RF amplifier; the RF amplifier output is connected tothe transmitting transducer; the receiving transducer is connected to aninput of the RF receiver gain and filter circuitry; the output of the RFreceiver is connected to a second channel input of the AID converter;and, the data analysis/display software controls signal generation,acquisition and display functions.
 45. The device of claim 41,comprising a transmitting transducer, wherein the transmittingtransducer and the receiving transducer are configured to be placed atcircumferential or longitudinal positions of the fluid filled container.46. The device of claim 31, comprising a guided wave generator operablycoupled to the transmitting transducer, which guided wave generatorproduces a shaped tone bust pulse at a specified frequency.